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(No Model.) 2 Sheets-Sheet 1.. w. A. DREWETT. .DIREGT ACTING STEAMENGINE.

No. 497,443. v Patented May 16, 1893.

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(No Model.)

Nd. 497,443. Patented May-16,1893.

.gmm/m d UNITED STATES,

WILLIAM A. DREIVETT, OF BROOKLYN, NEW YORK, ASSIGNOR TO MARSHALL PATENT.OFFICEa T. DAVIDSON, OF SAME PLACE.

DIRECT-ACTING STEAM-ENGINE.

SPECIFICATION forming part of Letters Patent No. 497,443, dated May 16,1893.

Application filed October 11,1892- I Serial No. 448.509. (No model.)

To all whom it may concern.-

Be it known that I, WILLIAM A. DREWETT, a citizen of the United States,residing in Brooklyn, Kings county, New York, have invented certain newand useful Improvements in Direct-Acting Steam-Engines, of which thefollowing is a specification.

My invention relates to direct acting steam engines and it has for itsobject to improve and simplify the construction of such engines and thearrangement and operation of the valve, and it consists in the variousfeatures of construction having the mode of operation substantially ashereinafter set forth.

Referring to the accompanying drawings wherein I have illustrated thepreferred em.- bodiment of my invention, Figure 1 is a longitudinalvertical section of the engine. Fig. 2 is a transverse vertical sectionon the line 22 Fig. 1. Fig. 3 is a horizontalv section through the steamchest; and Fig. lis an outline showing the preferred form of the ca inthe valve.

My invention relates generally to that class of direct acting engines inwhich there is a valve controlling the steam to the steam cylinder whichhas a combined oscillating and reciprocating movement, substantially asembodied in the well known Davidson engine, and the main object of mypresent invention is to simplify the construction and mode of operationof this class of valves. In the Davidson engine, the valve is operatedby mechanical means, so that it is first oscillated and then movedlongitndinallya distance to complete the closure of the main pistonports,

and this operation opens the valve piston ports in the steam chest sothat afurther movement of the valve is effected by direct steampressure. Moreover, in the Davidson engine the mechanical oscillationand reciprocation of the valve is accomplished by means of a pinconnected to the valve and extending into the exhaust port, in whichport is also arranged a cam controlled by the piston or piston rod ofthe engine, and which produces the oscillating and reciprocatingmovements of the valve. While this construction is effective, itrequires a large exhaust port, and the unbalanced area of the valve iscorrespondingly great involving as a ments of the valve, and strain andwear upon the pin and cam. Moreover,in this construction as beforeintimated, the valve is first oscillated and then reciprocated, and thisoscillation is accomplished by mechanical means. By my invention I amenabled to overcome. these and other disadvantages and to provide alighter steam chest, a valve of simple construction having lessunbalanced area, and to so arrange the parts that the oscillation ofvalve is accomplished by the direct steam pressure, instead ofby themechanical means, and I will now describe more in detail whatI havefound to be a practicable embodiment of my invention.

The steam cylinder A, is provided with a piston P, and piston rod, whichlatter is arranged to be connected with the pumping apparatus not shown,and mounted on the steam cylinder is the steam chest 0, which issupplied With steam through the pipe B, in this instance arranged toenter the steam chest at the side. i

Mounted in the steam chest is a valve D, which preferably is madesubstantially in the form of a cylinder, closely fitting the interior ofthe steam chest. This valve is provided with a spindle M, extendingthrough the head -of the steam chest, and on this spindle are isconnected as by a link 0', with the differ ential lever Q, which ispivotally mounted on some suitable part of the frame as the spindle Q,and'is connected to the piston rod P,

in any suitable way, as by a yoke Q and sliding block P. It will benoticed that this differential lever notbeing pivoted at the middle,allows the main piston of the engine to have a longer stroke thanthevalve, and by properly adjusting the contact pieces,l can so arrange theparts that the valve will be moved positively, and only at the propertime, and when tine piston is nearing the end of its stroke and in sucha manner that the valve will be moved to the proper extent to close themain steam ports and to open the valve piston ports in the steam chestand allow it to be moved to complete the opening of the main pistonports. In this way it insures the complete movement of the piston sothat the engine will do its full work, and a waste of steam owing to afailure of the piston to fully reciprocate in the steam cylinder isavoided. The valve D while being of a substantially cylindrical shape,is provided with heads E, E, which act as pistons for the valve, and itis also provided with a recessed openingf, arranged to connect the mainpiston ports G, G alternately with the exhaust port F, and ports oropenings 9, g, are also provided in the under side of the cylinder tocorrespond with the main piston ports in the different positions of thevalve. The steam chest is provided with valve piston ports 6, 6'extending from near the central portion of the chest to each endthereof, and the valve is provided with suitable recesses or ports.

corresponding to these central openings, so arranged that they will beopened and closed alternately as the valve operates substantially in themanner of the well known Davidson valve. In place of this arrangement,however, the ports may be constructed, and the pistons provided withvent holes Z so that the valve will be operated by the steamsubstantially as indicated in my application, Serial No, 448,507, filed011 even date herewith, or any other equivalent arrangement of ports andvalves by which the movement of the valve is accomplished substantiallyin the manner hereinafter set forth may be used.

As the steam enters the chest through the pipe 13 at the side, the valvecylinder is cut away at the side as shown at I3, and in order that itmay be thoroughly balanced, I preferably cut away a like portion on theopposite side, as at B and I may form a recess in the upper centralportion of the steam chest as indicated at B, so that the steam mayenter the valve on both sides through the ports or openings B, B

In order to produce the oscillation of the valve so that a proper valvepiston port will be opened or closed at each reciprocation, I form inthe upper portion of the cylindrical valve, an opening S which issubstantially lozenge shape, as shown in Fig. 4, that is, it hasparallel sides s, s, and inclined sides s 5 arranged at opposite ends ofthe opening, and extending into this opening is'a pin T, which issecured in the upper portion of the steam chest, and by hearingprogressively on the sides of the opening S, it will cause the valve tooscillate to open the valve piston ports.

The operation of the device will be readily understood by reference tothe drawings, in which the valve D is shown in its right hand position,and the contact piece 0, operated by the difierential lever has impingedupon the contact piece N, and as the piston P continues in its movementto the right, the valve will be reciproeated or moved longitudinally tothe left by the differential lever a sufficient distance to cause aclosure of the ports G, G' of the steam cylinder. Duringthis operationthe surfaces, of the opening S will move along past the pin T, and thevalve piston port E will be opened to admit steam behind the end ofpiston E of the valve, while the port cwill be in a position to exhauststeam from the steam chest in front of the piston E, and steamimmediately passes behind the piston E throwing the valve to completeits longitudinal movement. During this operation the pin T will be incontact with the portion 3 of the opening S of the valve, and this willcause the valve to oscillate while it is being moved under steampressure, so turning the valve as to close the valve piston port 6' tothe admission of steam, and open it to the exhaust, and at the same timeto open the valve piston port 6, to steam ready for the nextreciprocation. Steam having been admitted behind the piston P, it movesforward to the left, and as It approaches the end of its stroke thecontact piece 0, impinges on the contact piece U causing the valve D tobe reciprocated through a portion of its stroke and exposing the openingfrom the port a, allowing steam to enter behind the piston E, andclosing the ports G, G, when the steam will cause a further longitudinalmovement of the valve, and the p111 T, bearing 011 the inclined portion5 of the slot S, will produce an oscillation of the valve in the reversedirection from that before produced.

It will be seen that by this arrangement, the mechanical devices onlymove the valve through a portion of its longitudinal recip rocation,while the remainder of its longitudinal reciprocation and itsoscillation is produced directly by the steam acting on the piston headsof the valve controlled by the pin and slot. In this way I am enabled tosimplify the construction of the parts, attain a substantial balance ofthe valve, and produce the operation by means which are subject tolittle wear, and if, perchance, wear does occur 011 the pin it can bereadily repaired by being removed, and a new pin inserted or otherwise.More than that, the pin is more accessible than when extending into theexhaust port, and the port itself can be made smaller than in the oldconstruction, enabling the parts to be made lighter, and at the sametime all the advantages due to the combined oscillating andreciprocating valve are retained.

While I have thus described and illustrated the preferred embodiment ofmy invention, it is evident that the details of construction andarrangement may be varied by those skilled in the art without departingfrom the spirit thereof, and I do not therefore limit myself to theprecise construction and arrangement shown.

What I claim is- 1. In a direct acting engine the combination with thesteam cylinder, of a steam chest mounted thereon, a valve having acombined oscillatory, reciprocatory motion in the chest, a spindleconnected with the valve, a differential lever connected to be operatedby the engine piston to reciprocate the valve, and means connected withthe valve and steam chest to oscillate the valve, substantially asdescribed.

2. In a direct acting engine the combination With the steam cylinder, ofa steam chest mounted thereon, a valve fitting the chest, connectionsbetween the valve and the engine piston to partially reciprocate theValve ports in the steam chest, controlled by the valve to allow thevalve to be further reciprocated by the steam, and mechanical devicesconnecting the steam chest and valve for oscillatin g the valve,substantially as described.

3. In a direct acting engine the combination with the steam cylinder andsteam chest, of a valve having a longitudinal movement and anoscillatory movement, and means for oscillating the valve during thelatter portion of its longitudinal movement, substantially as described.

4. In a direct acting engine the combina tion with the steam cylinderand steam chest, of a cylindrical. valve having ports on its under sidecorresponding with the main piston ports in the cylinder, an opening inits side to receive the steam and an opening in its top, and a pinmounted in the steam chest and projecting into said top opening,substantially as described. Y

5. In adirect acting engine the combination with the steam cylinder, ofasteam' chest mounted thereon, a cylindrical valve having closed ends,mechanical connectionsbetween the valve and the engine piston forpartially reciprocating the valve, steam passages in the chestcontrolled by the valve to complete its reciprocation, and connectionsbetween the valve and steam chest for oscillating-the valve,substantially as'described.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

WM. A. DREWE'IT. Witnesses:

JOHN LOWE, GEO. O. EsKHOLINE.

